The Replacement

9PM, BBC1

This three-part thriller revolves around Ellen (Morven Christie, right), an architect who works at an impossibly cosy firm run by her best friends; though there is darkness in Ellen’s past, her loving chums and therapist husband have helped her to put it behind her. But when she hires Paula (Vicky McClure) to cover her maternity leave, Ellen starts to suspect that this overfamiliar cuckoo is trying to oust her from the nest.

The premise might sound like a straight-to-video thriller, but the execution is a cut above – and will certainly have you coming back for more.